1. Field of the Invention
The present invention relates to fittings of the type used for interconnecting hydraulic, pneumatic, and other high pressure fluid lines and their associated hardware.
2. Description of the Prior Art
Fittings are often used when it is necessary to connect pressurized fluid lines with one another and/or with associated hardware, such as actuators, manifolds, and the like. Fittings of this type typically include a tubular member defining a fluid passage, threaded connection portions on the ends of the tubular member for connecting the fitting with associated fluid lines, sealing portions adjacent the ends for perfecting a fluid-tight seal between the fitting and the associated fluid lines, and a central body portion formed radially larger than the tubular member and presenting at least one pair of diametrically opposed flats for engaging a wrench when connecting the fitting with the fluid lines or for mounting within brackets of a standard fluid line clamping system for preventing rotation of the fitting within the brackets.
A fitting used in such applications must have sufficient structural integrity to provide a leak-proof connection under high pressures. Thus, such fittings are commonly fabricated from any of a number of well-known metallic materials such as aluminum, steel, brass, etc. Examples of such fittings are those shown in Air-Way Manufacturing Company's Bulletin Number 105-78 of Olivet, Mich. Other examples include those disclosed in U.S. Pat. Nos. 3,414,220 granted Dec. 3, 1968 and 4,878,696 granted Nov. 7, 1989, both to Walker.
With all of these prior art fittings, the entire fitting is fabricated from metal, including the enlarged body portion. The body portion is either machined from bar stock and then brazed to the tubular member or, when possible, machined integrally with the tubular member. Examples of each are shown in the aforementioned Air-Way Bulletin. When forming the tubular member and body portion as one piece, it is common practice to begin with a piece of bar stock having a size and shape of the body portion. The one-piece fittings referenced above are made from hexagonal bar stock. The bar stock is then machined to form the radially smaller tubular member and threaded connection portions of the fitting. Examples of such fittings include numbers 070201, and 070119 shown in the aforementioned Air-Way Bulletin. Another example of this one-piece fitting for use with a standard plural line clamping system is shown in the previously cited Walker U.S. Pat. No. 4,878,696.
Although certain benefits are realized by machining the body portion and tubular member as one piece rather than forming the body separately from the tubular member and then brazing them together, (e.g., there are no weld joints which are prone to leaking), this type of fitting is still deficient in that a large amount of material is wasted by machining the radially smaller tubular member and threaded connection portions of the fitting from the oversized bar stock or forgings.
U.S. Pat. No. 4,854,613 to Reece et al, granted Aug. 8, 1989 discloses a plastic fitting having a metal internal liner. Although there is less wasted metal with this type of fitting over the above-described prior art fittings, this fitting is deficient in that the threaded connection portions are made from the plastic material which may be unsuitable for some high pressure applications.